Usually, in a gas bag module of a vehicle occupant restraint system, the gas bag is to be inflated as quickly as possible with the gas generated by the gas generator. In particular cases it is, however, desirable not to inflate the gas bag with the entire available volume of gas, or, more generally, to discharge gas, for which reason discharge openings are provided in the gas bag module, by the freeing of which the pressure in the gas bag can be limited.
Gas bag modules are known, in which an opening which is present in the gas bag fabric is initially closed by a membrane. This membrane can be removed or destroyed as required, in order to free the discharge opening.
From the prior art, in addition gas bag modules are known in which a discharge opening is arranged in the housing in direct proximity of the gas generator. In a closed state, the discharge opening is covered by a slider or the like which can be displaced to free the opening, whereupon the gas does not flow entirely into the gas bag, but rather partially flows toward the exterior through the discharge opening. Such sliders are moved magnetically or with the aid of pyrotechnics and have the disadvantage that they require a guide which represents an additional component and in addition represents an additional source for error. Also, such magnetic valves are often comparatively slow owing to the build-up of a magnetic field.
Furthermore, modules are known in which the module housing is provided with a pyrotechnic device such as a detonating cord so that on its activation an opening is produced in the housing through which gas can be discharged. For this, of course, high forces are necessary and sharp edges can occur on the housing.
It is therefore an object of the invention to provide a gas bag module with a discharge opening which can be freed quickly and reliably.